Example for removing unused fonts from RobotoTextView (https://github.com/johnkil/Android-RobotoTextView)

build.gradle

android.applicationVariants.all{ variant ->
    variant.mergeAssets.doFirst {
        File fonts = file("${rootDir}/build/exploded-aar/com.github.johnkil.android-robototextview/robototextview/2.0.1/assets/fonts")
        if (fonts.exists()) {
            for (File file : fonts.listFiles()) {
                if (file.getName().contains("RobotoSlab")) {
                    println("delete " + file.getName() + " font")
                    file.delete()
                };
            }
        }
    }
}